JPS62123715A - Formation of contact electrode - Google Patents

Abstract

PURPOSE:To properly execute the embedding of the contact hole formed in the insulating film on the Si substrate, to flatly form the surface of the titled contact electrode and to prevent the disconnection of the wiring by a method wherein the contact hole is filled with a metal layer generating no alloy spike by a plating method in the interface between the Si substrate and the wiring layer. CONSTITUTION:An oxide film 2 is formed on a substrate 1 and a photo resist film 5 is coat-formed thereon. A dry etching is performed on the insulating film 2 with a CHF3 plasma to form a contact hole 3. An Ag layer 6 is precipitated in the hole 3 by plating in a thickness equal to that of the insulating film 2. Lastly, an Al or AlSi alloy layer is formed thereon by a sputtering method and a mask of the desired wiring pattern is formed thereon using the photo resist. A dry etching is performed through the mask to obtain an Al or AlSi alloy wiring layer 4. Thus, the embedding of the contact hole is properly executed, the surface of this contact electrode is flatly formed and the disconnection of the wiring is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of forming contact electrodes for semiconductor devices.

[Conventional technology]

FIG. 3 is a cross-sectional view showing an example of a conventional contact electrode, in which an oxide film (2) is deposited to a thickness of about 1 μm on a silicon substrate (1), and a contact hole (3) is formed. , M or M-alloy wiring (4) is formed in a vine pattern.

Next, the formation method will be explained. A silicon substrate (
1) Form an oxide film (2) on top to a thickness of 1 μm. Next, a photoresist is applied on the oxide film (2), exposed to ultraviolet light using a mask, and developed to form a resist pattern of 22 m x 2 μm. Then, using this as a mask, the oxide film (2) is tri-etched with CHF3 gas to form a contact hole (3). Thereafter, M or i diagonal alloy was sputter-deposited on the entire surface, and electrodes and wiring (4) were further formed by photolithography and etching, as shown in the cross section of FIG.

[Problem that the invention seeks to solve]

By the way, in the conventional forming method, it is necessary to taper-etch the contact hole (3) as shown in FIG. It will be formed by directional etching, and as shown in FIG.
A-alloy wiring (4) or contact hole (3)
There is a problem that the film thickness of the wiring (4) becomes insufficient and there is a risk of disconnection.
Since the alloy wiring (4) was in direct contact with the silicon substrate (1), there were problems such as the occurrence of alloy spikes.

This invention was developed in order to solve the RJ problem as described above, and there is no need to taper-etch the contact hole (the size of the contact hole is small -C).
Another object of the present invention is to provide a method 5 for forming a contact electrode, which has no disconnection in wiring and does not generate alloy spikes.

[Means for solving problems]

In the method for forming a contact electrode according to the present invention, a contact hole formed in an insulating film on a 7-recon board is filled with a metal that does not cause alloy sparks at the interface with the 7-recon board by plating, and then i. On top of this, Sari-alloy wiring is formed.

[For production]

In this invention, as mentioned above, the contact hole is filled with a metal that does not cause alloy spikes at the interface with silicon, so the silicon substrate does not come into direct contact with Ag-based wiring, and the fAAJ alloy spike problem is solved. Moreover, since the surface of the insulating film is flat, the M or AAm alloy wiring can be formed to have a uniform thickness, reducing the risk of breakage.

〔Example〕

FIGS. 1A to 1D are cross-sectional views showing the main process steps of a method according to an embodiment of the present invention, in which the same reference numerals as in the conventional example indicate equivalent parts. First, an oxide film (2) with a thickness of approximately IPn is formed on the silicon substrate (1) after the process of forming diffusion regions (not shown) such as sources and drains, and a photoresist film [5] is formed on it. ) is coated to a thickness of 0.7 μm, exposed to ultraviolet light through a mask with a desired pattern, and developed to obtain a contact pattern of approximately 1 μm×1 μm (FIG. 1A).

Next, the oxide film (
2) is dry-etched with CHF3 plasma to form a contact hole (3) (Fig. 1B). Next, an insulating film (2) is formed in the contact hole (3) by plating using the method described later. Equal thickness Yuko A11 layer (6
) is precipitated (Fig. 1C). And finally S
The first layer is formed by sputtering an Ae wire alloy layer, and then a mask of the desired wiring pattern is formed using photoresist (
M or An! FF alloy wiring layer (4)
(Figure 1D).

Figure 2 is a sectional view showing the plating equipment used for A and 9 plating in this example process, where (7) is a container and (8) is a container (7).
) contained 4 potassium silver oxides [KA! 9 (C
N) 2) Aqueous solution), (9) is a holder made of an absolute material, Ql is a holder (9), and the contact hole side is exposed in the plating solution (8). The held silicon substrate, αη is plated i (8) 6C silicon substrate (AJ?! pole provided opposite to 10,
(6) is U electrode 0η2 positive.

A power source that provides a negative potential to the silicon substrate (2) is an electric heater installed under the container (7) to maintain the plating solution (8) at a temperature of 55 to 65 degrees Celsius, which is suitable for the progress of plating. .

Under the above conditions, a single DC current of 10A/d is applied from the power supply (6).
By flowing approximately 0.1 μm of Ag into the contact hole of the silicon substrate αQ, Ag is deposited at a rate of approximately 0.1 μm.

Although Ajj was used to fill the contact holes in the above embodiments, other noble metals may be used as long as they do not cause alloy spikes at the interface with silicon.

〔Effect of the invention〕

As explained above, in this invention, the insulating film 5 is formed on the PC board and the contact holes are filled by plating with a metal that does not produce alloy spikes at the interface with silicon, so that the contact holes are fine. Even in such a case, if the embedding is performed correctly and the surface is flat, the wiring formed thereon can be reliably formed without causing disconnection. Even if an M-based metal is used for the wiring, the problem of alloy spikes does not occur because the wiring does not come into direct contact with the silicon substrate.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing the state of deafness at the main stages of the method according to an embodiment of the present invention, Fig. 2 is a sectional view showing the configuration of a plating apparatus used in this embodiment, and Fig. 3 is a sectional view of a conventional contact electrode FIG. 4 is a cross-sectional view showing one example, and FIG. 4 is a cross-sectional view showing another example of a conventional contact electrode with fine dimensions. In the figure, (1) is a Noricon substrate, (2) is an insulating film (
oxide film), +3J is a contact hole, (4) is A
In the A35-A playback wiring, (6) is a buried metal layer. t2, The same symbols in the diagram indicate the same or corresponding parts 0 Agent Ken Hayase − ”< (@
udenshin\dennyo

Claims (2)

[Claims] (1) A step of forming an insulating film on a silicon substrate, a step of forming a contact hole in the insulating film through which the silicon substrate is exposed on the bottom surface, and even if it comes into direct contact with silicon, alloy spikes will occur at the interface. a step of filling the contact hole with a metal that does not contain aluminum by a plating method;
Or a method for forming a contact electrode, which includes a step of forming an aluminum-silicon alloy wiring. (2) The method for forming a contact electrode according to claim 1, wherein a noble metal such as silver is used as the metal filling the contact hole.